Bows not on the list:
Bow of arcing lightning - I've been told it was in Emerald, but I've never seen it in
Shivering shortbow of ivory - cold attack, in Emerald Forest. There are several of these, avg 20 or 22, I think
Bow of runed magic - wood-elf ranger near the ruined keep, avg 18, I think
Heavy Crossbow - 50lbs, the storm giants keep, no clue on avg
Longbow (can't remember the name) - ranger guildguard north of Arkham, avg 22, I think
holy white ashwood bow - elf rangers in Blackwater, 'searing light' attack, avg 20, I think
There are more that I can't think of right now.
By the way, DC, where'd you get the yellow bow of hardened acid?